Multiple condenser refrigeration systems



JAMES RHARNISH, BYE/MZYJQIW ATTORNEY J. R. HARNISH MULTIPLE CONDENSEH REFRIERATION SYSTEMS Filed April 19, 1966 Dec. 12, 1967 United States Patent O 3,357,199 MULTIPLE CONDENSER REFRIGERATIQN SYSTEMS James R. Hamish, Staunton, Va., assigner to Westinghouse Electric Corporation, Pittsburgh, Pa., a corporation of Pennsylvania Filed Apr. 19, 1966, Ser. No. 543,680 12 Claims. (Cl. 62-181) This invention relates to refrigeration systems having multiple condensers, and has as an object to facilitate the drainage of such condensers.

Multiple air-cooled or evaporative condenser coils are frequently used in large refrigeration and air conditioning systems. If all of the condenser coils are not the same size, or if the fan of one condenser coil is turned off, or if the fans of more than one condenser coil are turned olf, for reducing condenser capacity, diiiiculty will be encountered with liquid drainage unless each liquid line is trapped through an elevation difference of up to twenty feet which may be impractical.

This invention permits the use of different sizes of coundenser coils, and the cycling of individual condenser fans for capacity reduction, with no drainage problems regardless of the elevations of condenser coils and other cornponents connected thereto. Each condenser coil is drained by an expansion valve which feeds an associated evaporator at the rate at which liquid is condensed in that condenser coil. The condenser coil remaining in effective operation after the fans of the other condenser coils have been turned off, preferably is the largest condenser coil if the condenser coils have different sizes, and it supplies liquid through a heat exchange coil of an accumulator, and a subcooling control valve to the associated evaporator or evaporators.

This invention will now be described with reference to the annexed drawings, of which:

FIG. 1 is a diagrammatic View of a refrigeration system embodying this invention, and

FIG. 2 is a fragmentary diagrammatic view of a modification of FIG. 1.

Referring first to FIG. 1 of the drawings, a refrigerant compressor C is connected by discharge gas tube containing a pressurestat P, and tube 11 to condenser coil CA which is connected by tube 12 to heat exchange coil 13 within accumulator 14. The coil 13 is connected by tube 15 containing a subcooling control valve VA,. and tube 16 to evaporator means 17 which may be a single evaporator or may consist of multiple evaporators as disclosed in my copending application, Ser. No. 519,897, filed .l an. 11, 1966. The evaporator means 17 is connected lby tube 18 to the upper portion of the accumulator 14. The upper portion of the accumulator 14 is also connected by suction gas tube 19 to the suction side of the compressor C.

The disch-arge gas tube 1t) is also connected by tube 20 to condenser coil CB which is connected by tube 21 containing a subcooling control valve VB, and tube 22 to the tube 16. The discharge gas tube 10 is also connected by tube 24 to condenser coil CC which is connected by tube 25 containing a subcooling control valve VC, and the tube 22 to the tube 16.

The pressurestat P has a switch PS1 which opens when the discharge gas pressure decreases as a result of a de- 3,357,199 Patented Dec. 12, 1967 crease in condensing pressure, and has a switch PS2 which opens when the discharge gas pressure decreases further as a result of a further decrease in condensing pressure.

The condenser coil CA is the largest of the three condensers shown. It has a fan F1 for moving outdoor air over its surface. The fan F1 is driven by an electric motor M1 which is turned off when the compressor C is turned olf by conventional controls which are not shown. The condenser coil CB has a fan F2 driven by an electric motor M2, for moving outdoor air over its surface. The condenser coil CC has a fan F3, driven by an electric motor M3, for moving outdoor air over its surface. The motor M1 is directly connected to electric supply wires L1 and L2. The motor M2 is connected through the switch PS1 to the wires L1 and L2. The motor M3 is connected through the switch PS2 to the wires L1 and L2.

The subcooling control valves VA, VB and VC are expansion valves such as are disclosed in detail in my Patent No. 3,171,263, and operate to supply to the evaporator means 17 all of the refrigerant which is condensed within the condenser coils CA, CB and CC respectively, while maintaining a predetermined amount of subcooling, which may be 10 F. subcooling at a condensing temperature of F. of the condensed refrigerant. While it is preferred that these valves be subcooling control valves, they could be other expansion valves such as high pressure float operated valves which supply refrigerant at the rate at which it is condensed, but without the subcooling advantage. The valve VA has a diaphragm chamber 3i), the outer portion o-f which is connected by a capillary tube 31 to thermal bulb 32 in heat exchange contact with the tube 12, and the inner portion of which is connected by a capillary equalizer tube 33 to the interior of the tube 12. The valve VA thus responds to the temperature and the pressure of the refrigerant flowing through the tube 12. The valve VB has a diaphragm chamber 34, the outer portion of which is connected by a capillary tube 35 to thermal bulb 36 in heat exchange contact with the tube 21, and the inner portion of which is connected by a capillary equalizer tube 37 to the interior of the tube 21. The valve VB thus responds to the temperature and the pressure of the refrigerant flowing through the tube 21. The valve VC has a diaphragm chamber 40, the outer portion of which is connected by capillary tube 41 to thermal bulb 42 in heat exchange contact with the tube 25, and the inner portion of which is connected by capillary equalizer tube 43 to the interior of the tube 25. The valve VC thus responds to the temperature and the pressure of the refrigerant llowing through the tube 25. The valves VA, VB and VC could be internally equalized.

In FIG. 1, the fan motor M2 is turned olf when there is a predetermined decrease in condensing pressure, and the fan motor M3 is turned off when there is a further decrease in condensing pressure. FIG. 2 is a modification of FIG. 1 in which an outdoor thermostat T is used instead of the pressurestat P. The thermostat T has a switch TS2 connecting the motor M2 to the wires L1 and L2, and has a switch TS3 connecting the motor M3 to the wires L1 and L2. The switch TS2 opens and deenergizes the motor M2 when there is a predetermined decrease in outdoor temperature, and the switch TSS opens and deenergizes the motor M3 when there is a further decrease in outdoor temperature.

The system is overcharged with refrigerant so that there is always some refrigerant liquid within the accumulator 14 in contact with the coil 13.

OPERATION The compressor C supplies discharge gas through the tube 10, the pressurestat P, and tube 11 into the condenser coil CA. Liquid flows from the coil CA through the tube 12, the coil 13 within the accumulator 14, the subcooling control valve VA, and the tubes 15 and 16 into the evaporator means 17. Discharge gas is also supplied through the tubes and 20 into the condenser coil CB. Liquid ows from the latter through the tube 21, the subcooling control valve VB and the tubes 22 and 16 into the evaporator means 17. Discharge gas also flows through the tubes 10 and 24 into the condenser coil CC. Liquid ows from the latter through the tube 25, the subcooling control valve VC, and the tubes 22 and 16 into the evaporator means 17. The subcooling control valves VA, VB and VC overfeed the evaporator means 17, and g-as and unevaporated refrigerant liquid ow from the evaporator means 17 through the tube 18 into the accumulator 14 where the excess refrigerant liquid is evaporated by heat from the liquid owing through the coil 13 within the accumulator 14, the liquid being further subcooled by this action. Gas separated from the liquid within the accumulator 1'4 flows through the suction gas tube 19 to the suction side of the compressor C.

If the load on the system decreases, or the outdoor ambient temperature is low, so that all of the condensing capacity is not required, the pressurestat P responds to the resulting decrease in discharge pressure, and opens its switch PS1, deenergizing the fan motor M2, stopping the fan F2, and effectively placing the condenser coil CB out of operation although there may be a slight thermal movement of air over its surface, and a slight amount of refrigerant condensed within it, which refrigerant will be supplied by the valve VB to the evaporator means 17. If there is a further decrease in the load on the system, or if there is a further decrease in the outdoor temperature, so that all of the remaining condensing capacity is not required, the pressurestat P responds to the further decrease in discharge gas pressure, and opens its switch PS2, deenergizing the fan motor M3, stopping the fan F3, and effectively placing the condenser coil CC out of operation, although there may be a slight thermal movement of air over its surface, and a slight amount of refrigerant condensed within it, which refrigerant will be supplied by the valve VC to the evaporator means 17.

The condenser coil CA remains continuously in operation during operation of the system, and supplies sufficient refrigerant liquid through the coil 13 within the accumulator 14 to provide such subcooling of that liquid that its refrigeration effect is sufiicient for the valve VA to overfeed the evapor-ator means 17. As previously explained, if the condenser coils have different sizes, the coil CA should be the largest so that it can supply the most liquid through the coil 13 and the subcooling control valve VA into the evaporator means 17.

Decreases in the temperature of the outdoor air flowed over the surfaces of the condenser coils, reduce the condensing capacity required, and as will be explained in the following in the operation of FIG. l modified as shown by FIG. 2, an outdoor thermostat T can be used to place the condenser coils CB and CC effectively out of operation. Referring now to FIG. 2, switch TS2 of the thermostat T opens when there is a predetermined decrease in outdoor temperature, deenergizing the fan motor M2, stopping the fan F2, and effectively placing the condenser coil CB out of operation. When there is a further decrease in the outdoor temperature, the switch T S3 of the thermostat T opens, deenergizing the fan motor M3, stopping the fan F3, and effectively placing the condenser coil CC out of operation.

The control system of FIG. l is preferred since it would sense decreases in outdoor temperature, and in large systems, the variable compressor loading would limit the effectiveness of the control system of FIG. 2.

What is claimed is:

1. A refrigeration system comprising a refrigerant compressor, irst and second condenser coils, means including a discharge gas tube connecting said coils to the discharge side of said compressor, an accumulator, a heat exchange coil arranged to heat liquid within said accumulator, a liquid tube connecting said first condenser coil to said heat exchange coil, evaporator means, a first expansion valve connected to said heat exchange coil and to said evaporator means, a second expansion valve connected to said second condenser coil and to said evaporator means, means for adjusting said first expansion valve to supply refrigerant to lsaid evaporator means at the rate at which refrigerant is condensed within said firstcondenser coil, means for adjusting said second expansion valve to supply refrigerant to said evaporator means at the rate at which refrigerant is condensed within said second condenser coil, means connecting said evaporator means to said accumulator, and a suction gas tube lconnecting said accumulator to the suction side of said compressor.

2. A refrigeration system as claimed in claim 1 in which said first expansion valve is a subcooling control valve, and in which said means for adjusting said first expansion valve responds to the temperature and the pressure of the condensed refrigerant flowing from said first condenser coil.

3. A refrigeration system as claimed in claim 2 in which said second expansion valve is a subcooling control valve, and in which said means for adjusting said second expansion valve responds to the temperature and the pressure of the condensed refrigerant owing from said second condenser coil.

4. A refrigeration system as claimed in claim 1 in which said second expansion valve is a subcooling control valve, and in which said means for adjusting said second expansion valve responds to the temperature and the pressure of the condensed refrigerant flowing from said second condenser coil.

5. A refrigeration system as claimed in claim 3 in which a fan is provided for moving outdoor air over said second condenser coil, in which an electric motor is provided for driving said fan, and in which means is provided for deenergizing said motor when condensed refrigerant from said second condenser coil is not required by said evaporator means.

6. refrigeration system as claimed in claim 1 in which a fan 1s provided for moving outdoor air over said second condenser coil, in which an electric motor is provided for driving said fan, and'in which means is provided for deenergizing said motor when condensed refrigerant from said second condenser coil is not required by said evaporator means.

7. A refrigeration system as claimed in claim 6 in which said rst expansion valve is a subcooling control valve, and in which said means for adjusting said first expansion valve responds to the temperature and the pressure of the condensed refrigerant flowing from said first condenser coil.

8. A refrigeration system as claimed in claim 7 in which said second expansion valve is a subcooling control valve, and in which said means for adjusting said second expansion valve responds to the temperature and the pressure of the condensed refrigerant flowing from said second condenser coil.

9. A refrigeration system as claimed in claim 8 in which said means for deenergizing said rnotor includes means responsive to the pressure of the high pressure refrigerant owing in said system and having a switch connected in the energizing circuit of said motor which opens when said pressure is reduced to a predetermined pressure.

10. A refrigeration system as claimed in claim 7 in which said means for deenergizing said motor includes means responsive to the pressure of the high pressure refrigerant owing in said system and having -a switch connected in the energizing circuit of said motor which opens when said pressure is reduced to a predetermined pressure.

11. A refrigeration system as claimed in claim 6 in which said means for deenergizing said motor includes means responsive to the pressure of the high pressure refrigerant owing in said system and having a switch connected in the energizing circuit of said motor which opens when said pressure is reduced to a predetermined pressure.

5 temperature, said switch being in the energizing circuit of said motor.

References Cited UNITED STATES PATENTS 10 2,278,242 3/ 1942 Chapman 62-183 XR 2,770,100 11/1956 Raney 62--196 XR 2,952,991 9/1960 St. Pierre 62-181 XR MEYER PERLIN, Primary Examiner. 

1. A REFRIGERATION SYSTEM COMPRISING A REFRIGERANT COMPRESSOR, FIRST AND SECOND CONDENSER COILS, MEANS INCLUDING A DISCHARGE GAS TUBE CONNECTING SAID COILS TO THE DISCHARGE SIDE OF SAID COMPRESSOR, AN ACCUMULATOR, A HEAT EXCHANGE COIL ARRANGED TO HEAT LIQUID WITHIN SAID ACCUMULATOR, A LIQUID TUBE CONNECTING SAID FIRST CONDENSER COIL TO SAID HEAT EXCHANGE COIL, EVAPORATOR MEANS, A FIRST EXPANSION VALVE CONNECTED TO SAID HEAT EXCHANGE COIL AND TO SAID EVAPORATOR MEANS, A SECOND EXPANSION VALVE CONNECTED TO SAID SECOND CONDENSER COIL AND TO SAID EVAPORATOR MEANS, MEANS FOR ADJUSTING SAID FIRST EXPANSION VALVE TO SUPPLY REFRIGERANT TO SAID EVAPORATOR MEANS AT THE RATE AT WHICH 